Organic Light-Emitting Diode, OLED display apparatus, also known as organic electroluminescent display apparatus, it is a new flat panel display apparatus, because of its advantages of simple fabrication process, low cost, low power consumption, high luminous brightness, adaptation to a wide working temperature range, thin volume, fast response time, and easy to achieve color display and large screen display, easy to achieve matching with integrated circuit drivers, easy to achieve flexible display, etc., and thus has broad application prospects. The OLED, according to the driving methods, can be divided into two categories of passive matrix OLED type and active matrix OLED, AMOLED.
Thin Film Transistor, TFT is the main driving element in the AMOLED display apparatus, which is directly related to the development direction of high performance flat panel display apparatus. The existing TFT backplane has variety kind of structures, and the material of the active layer of the thin film transistor to fabricate the corresponding structure also has variety kinds of materials. For example, in the same TFT backplane, it is possible to simultaneously use a polysilicon material having high electron mobility and a uniformly current outputting, and a non-polysilicon material having a fast switching speed and a low current leakage to form a driver TFT and a switching TFT, respectively. The TFT backplane can select to use different TFTs depending on the different requirement of functions.
However, the inventors of the present application have found from the long term research, within the conventional technology, in order to improve the reliability and electrical performance of the driver TFT, the gate insulating layer of the TFT is used as the structure of the oxide plus nitride, however, in the high temperature process of the TFT after the deposition of the nitride, the nitride will diffuse, which will contaminate the non-polysilicon material of the switching TFT, thus affecting the performance of switching TFT with non-polysilicon material and reducing the performance of the entire TFT backplane.